


Operation: Save Byleth!

by UnapologeticallyMeatwad



Series: The Black Eagle Spy Ring! [1]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Action/Adventure, Alternate Universe - Modern Setting, Alternate Universe - Spies & Secret Agents, F/F, Helicopters, Non-Binary Byleth, Nuclear Launch Codes, Trains, no beta we die like Glenn
Language: English
Status: Completed
Published: 2020-09-25
Updated: 2020-09-25
Packaged: 2021-03-08 03:27:41
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,221
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26649010
Author URL: https://archiveofourown.org/users/UnapologeticallyMeatwad/pseuds/UnapologeticallyMeatwad
Summary: Agent Byleth Eisner is kidnapped by Those Who Slither in the Dark after a mission to destroy nuclear launch codes is botched. Thankfully for Arundel, Byleth knows the codes and he intends on selling those codes to Rhea.But the Black Eagle Strike Forces leaves no one behind. Edelgard will do everything in her power to save her beloved.
Relationships: Edelgard von Hresvelg/My Unit | Byleth
Series: The Black Eagle Spy Ring! [1]
Series URL: https://archiveofourown.org/series/2156865
Comments: 4
Kudos: 20





	Operation: Save Byleth!

**Author's Note:**

> If you want to have the max amount of fun reading this wild adventure, listen to the Mission Impossible: Fallout soundtrack while reading. It slaps. 
> 
> https://www.youtube.com/playlist?list=PLim3m5NnkYFeCOsJA6yE6xBBO5uAnG4lo
> 
> Thanks for reading!

At 1400 hours, the high speed bullet train will depart from Garreg Mach Academy Station to Enbarr. The journey takes thirty minutes. In this time, Arundel (Codename: Thales) will meet with Rhea (Codename: Immaculate One) and make a business transaction. Rhea’s buying nuclear launch codes, Arundel is just taking money. 

But it’s not that simple. Never is. 

One month prior, Agent Byleth Eisner was captured by Those Who Slither in the Dark. From insider intel, Team Leader Edelgard von Hresvelg has determined that Byleth is still alive and will be onboard the, sealed off in a capsule that can only be opened by a passcode.

What Rhea doesn’t know is the launch codes were destroyed. The only one who knows them is Byleth. Rhea thinks she is buying a stack of papers when really she’s buying a human vessel. The stakes have never been higher.

Edelgard gets up from her seat at the back of the train. Brown wig and sunglasses. High waisted suit pants and a red blouse to her black blazer. She makes her way through the train. “Is everyone in position?” she whispers.

“ _ Yes! _ ” Bernadetta squeaks, crouched besides Byleth’s container surrounded by mission gear.

“ _ Affirmative, Lady Edelgard _ ,” Hubert coos into his mic. “ _ Dorothea and Petra accounted for as well _ .” They are a mile out, prepared to steal a helicopter at any given moment. 

“Don’t move until my signal,” Edelgard mutters. “Linhardt?”

“ _ Yes, _ ” he feigns a yawn. He’s the guy in the van. “ _ Caspar’s practicing his punches but he’s with me _ .”

“He doesn’t need to practice,” Edelgard snips.

“ _ You tell him that _ .”

“Fine,” Edelgard rolls her eyes and then narrows them. “Ferdinand?”

“ _ Yes _ ,” Ferdinand says and there is a heavy pause. Everyone waits with bated breath. “ _ I’ll admit though… _ ”

And everyone groans.

Ferdinand continues, “ _ I do not understand why I cannot work on the field. I’m very good and _ —”

“Ferdie,” Edelgard hisses between her teeth. “You are superior to driving a bullet train when compared to me. Please.”

Another pause. “ _ So I am! I shall add this to my list. _ ”

“Good,” Edelgard mutters and steps forward. She almost calls for Byleth’s confirmation out of instinct but she knows it’s futile. 

_ Soon my love. Soon _ .

From afar, Edelgard can see the tops of Arundel’s balding scalp and Rhea’s elegant, emerald hair. Their heads bob up and down, deep in conversation. Quick round of poison darts and it’ll look they’re sleeping like the other passengers. Edelgard steals the briefcase and mission accomplished. She steps forward and something grabs her by the hand. Her shoulders retract like bat wings and she whirls around. 

“Edelgard?!” Dimitri decrees. He leans back, a fake mustache under his nose. With the thick glasses, he looks ridiculous. “What are you doing here? Can you believe it, Claude?”

Edelgard looks back. Arundel shifts to get up and she swipes off her wig, kicking it under Dimitri’s chair. “Compromised, Code Red,” she whispers. 

Claude raises an eyebrow playfully. “Ooh, Big D, why’d you do that?”

Dimitri blinks. “I don’t understand.”

Edelgard could rip his face off. “Why are you here?”

“Oh, I’m not sure,” Dimitri looks to Claude. “My good friend, Claude, just asked me to wear this silly outfit and get on a train with him.”

Claude rolls his eyes. “We’re  _ working _ . And so is Edelgard, apparently separate from us.”

Dimitri lets out a hearty chuckle. “Well, there you are. So what’s the scheme, friends?”

“I’m not working with you,” Edelgard snips.

“Be calm,” Claude grabs Dimitri’s thigh as Arundel appears from behind.

“Why, if it isn’t my favorite nephew,” Arundel says with that usually oily slick that hardly passes for anything kind. “And Edelgard. What  _ are _ you doing here?”

Edelgard catches Arundel’s side eye fast. “Just visiting my father in Enbarr.”

Arundel doesn’t flinch. “With your Academy friends? Last I heard, the three of you had a big fight.”

Claude leans, blocking Dimitri out of view. “It be like that sometimes. We just bumped into each other, and it’s pretty awkward.” 

“ _ Edelgard, nooooo! _ ” Bernadetta screams so loud into Edelgard’s radio she’s afraid Arundel will hear. But if he does, his face stays as smooth as ever. 

“Uncle, we should catch up!” Edelgard smiles. “We land in ten minutes, it shouldn’t be too much of a strain on you.”

Arundel shakes his head and swats at the air in annoyance. “Fine.”

He trails ahead and Edelgard follows, silently praying that Berandetta can come up with something —  _ anything _ — else. 

“ _ Edelgard, _ ” Bernadetta. “ _ X-Ray glove. Back right pocket. _ ”

Thank God. Bernie’s best when alone and surrounded by her gadgets.

Edelgard smiles to herself and discreetly reaches for it. It’s a thin screen that fits across her palm, and like an X-Ray, it can see through the surfaces of things it’s on. Powered by heat. She slides into the booth besides Arundel and locks eyes with Rhea, a briefcase on the table between them. 

Rhea’s baby soft face twists into harsh lines immediately. “Edelgard.”

“Yes, yes,” Arundel drawls. “Edelgard. Don’t lie to me.”

Rhea leans back with a pleasant smirk, harsh lines already gone. “Did Edelgard used to work for you, Arundel?”

“Yes, for a long time,” Arundel coos, playfully scratching Edelgard’s chin like she’s a cat. “She resigned after she fell desperately in love with that former ward of yours, Byleth was it?”

Rhea looks like a child sitting on Santa’s lap. “You have bad taste in partners.”

Edelgard sticks her tongue out. 

Arundel continues, “And in my mercy, I let her live with the request she leaves the country and yet here we are.”

“Here we are,” Rhea repeats. 

Edelgard sighs. 

“ _ Tell him you want to work for him again, _ ” Dorothea says pointblank. Dorothea: Master Masquerader. Perfect partner in crime to Hubert. “ _ That you realized in your isolation that it was a mistake to walk. _ ” 

Edelgard can hear choking in the background of the call. Definitely Hubert chloroforming without the signal. 

Edelgard looks to Arundel and places one hand on his knuckle and tells him just that. 

Arundel cocks an eyebrow in amusement. “Is that to?”

“Oh please,” Rhea crosses her arms. “Don’t tell me you’re falling for that.”

Arundel glows. “Rhea, you don’t know Edelgard like I do. She’s quite proud of herself. Tell me about your friends. Have you kept in touch and are you ready to kill every last one of them?”

Edelgard double takes. “Why are my friends targets?”

“Because I  _ detest _ you,” Arundel presses his teeth together. “Tell me you’ll kill them.”

Edelgard nods and stretches her arms high in the air, it’s incredibly awkward. She yawns and wow, it almost makes her cringe. What a horrible performance.

“ _ I am also a better actor than Edelgard! _ ” Ferdinand chimes in with inspiration.

Roasted. Edelgard rests her elbow on the table, hand falling onto the briefcase. She keeps her body open and vulnerable to Arundel, so he could shoot her if he wanted to. 

Rhea slaps Edelgard’s hand away from the briefcase. “Don’t touch that you awful girl!”

Edelgard retracts her hand, hoping that gave Bernie enough of a reading. 

* * *

In the backroom, Bernadetta drops at least five things as the code flashes on her reader. 

6-1-9-5-8-0.

She runs to the capsule and begins mashing buttons.  _ Please be it, please be it… _

* * *

Mid speech about her new allegiance, there is a soft  _ click  _ from underneath the table. Only one of Rhea’s hands is visible. She cocks an eyebrow. “Arundel, you take Edelgard back to Those Who Slither, and we don’t have a deal.”

Arundel turns to Edelgard and laughs. “Well, then. Poo poo to you then, my child. I assume you are about to poison her with that gun.”

“Any sudden movement and yes, I will,” Rhea might as well lick her lips at this point. 

Edelgard leans back, eyes frosty. “Rhea, do you know what’s in this briefcase?”

“It’s paperwork,” Arundel answers, a little too fast. Ha, Edelgard knew it. She knew Rhea didn’t know.

And Rhea notices Arundel’s haste.

* * *

Out in the backroom, the code flashes red. Every single time she tries it. 6-1-9-5-8-0. 6-1-9-5-8-0. 6-1-9-5-8-0.

6-1-9-5-8-0.

6-1-9-5-8-0.

6-1-9-5-8-0.

Red red red red red RED RED RED RED.

“ _ Edelgard, I need a second read, _ ” Bernadetta squeaks.

“ _ Hold on _ ,” Linhardt cuts in. “ _ Let me take a look, hold it in front of your cam please. _ ”

* * *

Edelgard smiles to herself, and speaks very slowly. “I’d explain Rhea, but unfortunately we’re about to pull up in Enbarr.  _ Oh, if only we had more time. _ ”

* * *

Up at front, Ferdinand repeats that to himself. “If only we had more time… oh no, she doesn’t mean…”

“ _ Yes, _ ” Hubert says fast, always first to criticize Ferdinand. “ _ Miss the stop _ .”

“But I practiced so hard!” Ferdinand whines. “It’s my landings that make me superb at—”

“ _ I will  _ **_burn_ ** _ your tea collection. Oh and Lady Edelgard will die if you don’t. _ ”

“...very well.”

* * *

“In the backroom,” Edelgard starts with a coy ass smile. “Is Byleth. They’re alive, trapped in a capsule, and they have the nuclear codes. Arundel is merely selling you the code to open that capsule… you will need to transport Byleth and get the codes from them.”

Rhea looks to Arundel very slowly and her voice is sharp as icicles. “Is that so.”

* * *

“ _ Bernie _ ,” Linhardt says, jolting Bernadetta back to reality. “ _ You had the code upside down. Try again. _ ”

“Oh,” Bernie’s face goes so red, at least no one can see. “Don’t tell anyone.”

0-8-2-6-1-9.

The capsule opens and Byleth flops forward, landing in Berandetta’s arms, knocking the two of them to the floor. 

Bernadetta rolls over and looks at them. They’re pale, skin sweaty and clammy. Just black slacks and a loose white blouse that looks very lived-in. It’s what they had on when they got captured. “Byleth…”

Byleth’s wide eyes snap open and their limbs move like noodles. “I’m drugged,” they croak, reaching out with their hand. “Adrenaline. Now. While you set it up, explain what happened.”

“ _ Ooh, Caspar, get ready, _ ” Linhardt chides. “ _ Welcome back, friend. _ ”

Byleth smiles through the pain. “Operation Uppercut?”

Caspar then proceeds to blow out everyone’s ears with a mighty “ **_OPERATION UPPERCUT HUAAAAH!”_ **

* * *

Everyone on the train starts screaming at once as Enbarr station zooms past in view. Both Arundel and Rhea turn to see the commotion, and that gives Edelgard the chance. She slips halfway under the table and wraps her ankles around Rhea’s calves, yanking her under, Rhea’s chin smashing against the table and drawing blood.

* * *

“Okay,” Bernadetta winces as she prepares the adrenaline shot. “Caspar, stop swinging! I need them to stay still.”

“ _ Sorry. Excited. _ ”

Byleth’s hands drop to their thighs, encased in iron gloves synced with Caspar in the van. He swings, Byleth swings in sync with him.

It gives Byleth the fighting prowess they’ll need when drugged like this. Even the adrenaline can’t help that. 

Needle goes in and Byleth howls like a Wall Street tycoon reeling from a bump. They pat Bernie on the side and sprint out the door.

Bernadetta goes to a crouch again. “Hubert… we need the helicopter I think.”

* * *

“Of course we do,” Dorothea laughs into her walkie, standing over the dashboard. “Sorry, Hubie’s indisposed.”

Besides her, the final security guard is making out hard with Hubert’s poison lips, and then slumps. 

“I hate leading people on,” Hubert groans, looking out the window. Petra’s already on board and lifting off. “ETA five minutes.”

* * *

Byleth runs like Hell, stumbling through absolutely everything. But they have speed and they blaze ahead. Even if it takes grabbing onto passing seats to stay afloat, they do it.

It’s El after all.

Byleth sees Edelgard going hand to hand with Rhea — who of course is an expert grappler — and with Arundel who only knows how to look cool like he’s fighting hand-to-hand. 

Caspar swings so hard that the punches literally propel Byleth forward, and they make such short work of Arundel, Byleth is embarrassed for them. The guy just bounces around like a ragdoll and hits the floor, bleeding from everywhere he can. People are screaming and backing off as the fight with Rhea gets wild. 

* * *

“Byleth!” Dimitri calls out from the back. “Byleth, do you see me? It’s me, Dimitri!” 

“D,” Claude whispers. “Even if Edelgard gets what she wants out of this, a shit ton of people are watching. Black Eagle Strike Force is compromised… and the jobs go to us.”

Dimitri shoots Claude a look. “Claude.” He holds this gaze for a long time and Claude looks away.

So Dimitri grabs Claude by the chin and makes them lock eyes. “I’m upset with Edelgard too, for refusing to collaborate with us. But she’s our friend and was under a lot of pressure back then. Have a heart.”

“God dammit,” Claude says in a tiny voice, and pulls out his briefcase from underneath, and hands Dimitri a gun with a satellite dish on the end. “It’ll knock everyone out and wipe memories. Move fast.”

Dimitri holds the gun to his face and nods.

* * *

Byleth gets between Rhea and Edelgard, clobbers at Rhea. God they hate Rhea.

Their fists match and crash into each other, and even though Byleth has iron on and Rhea is bare fisted, she just doesn’t seem phased. 

Byleth is pretty sure the woman is on some kind of steroid — and it’s killing the circuitry to the gloves. That becomes obvious when one of their arms just loses all sense of direction and flops over, with the rest of Byleth. 

Rhea yanks Byleth in by the blouse and trains a regular gun on Edelgard’s head. She smirks. “What’s your exit?”

Edelgard doesn’t say anything. 

Byleth coughs and looks over to their beloved El. A long hard look. No tears, just a quiet nod.

“Helicopter,” Edelgard grunts. 

“Good,” Rhea backs up. “You follow me. No funny shit. And tell your driver to slow this train down so we don’t fall off.”

“Ferdie, did you catch that?” Edelgard asks. 

“ _ Yes, _ ” Ferdinand tells her with some sorrow. “ _ Edelgard, you are the superior field agent and you will make this work. _ ”

* * *

Petra flies over the train, kicking out the rope ladder to run along the carts. She dips down and God this is dangerous. She is  _ just _ skimming the trees but that is what it takes to save Byleth.

She doesn’t even know if they’re coming with her; walkie died when she hit the air. 

So she sighs with some relief when Byleth stumbles over the top of the train. They all expected Byleth to be drugged up, so that makes sense that they can barely stand.

Though it does fill Petra with rage. 

And it makes her even more angry when Rhea climbs onto the top, holding something that is almost certainly a gun. She kicks Byleth in the stomach and they roll over, fingers feebly gripping onto the metal plates to hang on. 

And then Edelgard comes on. The gun is on Edelgard. 

* * *

“Stop hurting them!” Edelgard screams, lunging at Rhea, backing off when the gun levels with her chest. “You’re awful.”

“Eh,” Rhea snarks, lifting Byleth up by the hair. 

Edelgard winces, fists curled up. There is nothing she can do here.

The rope ladder lowers and Rhea hurls Byleth into it. “Climb, you idiot.”

Byleth hangs there for a second, corpse-like, and then finally starts moving. They climb slowly, but Rhea doesn’t seem to mind. She’s got the gun, she’s got the power, and she can still have one hand on the ladder so there’s no easy out for Petra.

When Rhea feels good, she latches on and waves Petra off. 

The helicopter pulls away, it’s up to Petra now to save Byleth. It’s out of Edelgard’s hands.

Fuck that’s not fair.

Rhea still has a gun, and she catches up with Byleth fast. Petra can’t even cut the ladder before Rhea makes it.

A good agent would just crash the helicopter and kill the three of them. That’s how Arundel runs his ops, it’s how most people do it. 

But the Black Eagle Strike Force is different. Petra is different. 

Edelgard sprints down the train, fighting the velocity that wants to throttle her into roadkill. She uses everything she has and leaps off the train, grabbing onto the bottom rung of the rope ladder, dangling from it as it pulls hundreds of feet into the air. 

_ Don’t look down _ , she says as she does that very thing. Her whole body waves in the wind but she is not dying here. She reaches up and grabs the second rung. She pulls up and she moves. 

Rhea hasn’t noticed yet. 

Edelgard moves far faster than recommended, nearly slipping off five times. But she moves faster than a normal person would and it’s not long before she catches up with Byleth and Rhea, all three of them at the top of the ladder.

Edelgard grips Rhea’s ankle hard, and pulls really fucking hard.

Rhea screams and falls off of Byleth, flying off the ladder—

—and grips onto Edelgard’s ankle, taking her with her.

The wood burns and shreds Edelgard’s palms as she is torn down the entire rope ladder, but she manages t hold the fuck on. Bleeding palms and all, Edelgard hangs from the bottom rung again, Rhea holding onto Edelgard’s ankle, Rhea’s entire body weighing down on bleeding hands that are about to tear into two.

Edelgard doesn’t know what to do. She can’t move, her whole body is at capacity. This is it. She looks up, Byleth makes it into the helicopter at least. Good. They deserve to live. 

And then Byleth leaps out of the helicopter and throttles towards them.

It’s a massive drop, but Agent Byleth Eisner pulls it off with splender, dropkicking Rhea in her stupid face. Rhea’s scream is ear splitting and can only be heard for a half second before she drops out of range. 

Byleth catches the final rung at the last minute and that’s it. That’s the mission.

Edelgard glances down. She can’t help it, she wants to see that body hit the ground—oh no, maybe she doesn’t. That’s gross. Don’t do that.

She looks to Byleth whose face is twisted in agony.

“I just broke my fucking foot,” Byleth moans. “Holy shit, holy shit, holy shit…”

Edelgard feels the pain too. She grits her teeth and throws her arms through the rung and hooks in by the armpits. It hurts like a bitch, but at least that area of her body isn’t torn yet. They’ll land soon. 

Edelgard looks to Byleth. “Focus on my eyes, my love.”

Byleth nods through the tears. “I always am, El.”

“I’m here with you,” Edelgard rasps. “We’re…”

Byleth doesn’t let her finish, they just go for the kiss. 

This is the Black Eagle Strike Force. They do missions that no one else can. Fuck the other spy groups, none of them have regrets. Wait. No. Edelgard… does, yeah, she has a regret.

Edelgard looks at the rolling green below, looks at the train. Thinks about the corpse that will be found in a few days. This was Plan  _ B _ . 

There was a Plan A that was so easy and simple. But  _ someone  _ blew her cover.

Byleth kisses Edelgard again and it makes it hard to think. 

But Edelgard knows that next time, she is going to text Dimitri and Claude in advance not to show up at her ops.

**Author's Note:**

> Plz let me write the next Mission Impossible. Anyways, just for fun: 
> 
> Byleth & Edelgard - The Badasses  
> Hubert - The Seductress  
> Dorothea - The Masquerader  
> Petra - The Swiss Army Knife  
> Linhardt - The One in the Van  
> Bernadetta - The One with the Gadgets  
> Ferdinand - The Odd Job Man  
> Caspar - The Muscle
> 
> Thanks!
> 
> You can [follow me on Twitter](https://twitter.com/IAmLordMeatwad) for tweets about my cats and fanfic, and [follow me on Insta](https://www.instagram.com/katrinajagelski/) for similar stuff. Occasionally I do live reads for my original fiction and fanfic.


End file.
